The sixth chapter of Massekhet Eiruvin returns to the discussion of eiruvei hatzeirot – the laws that regulate how to arrange to permit residents of a courtyard to carry within it. In particular, this chapter focuses on the residents themselves. All of the residents need to participate in the eiruv, but if one of them did not participate, even on Shabbat he can rectify the matter by ceding his ownership to another resident who did participate.
One of the central questions dealt with is who is considered a resident of the courtyard for the purpose of creating the eiruv, and what needs to be done if someone does not want to participate.
The Mishna (61b) brings a disagreement between Rabbi Meir and Rabbi Eliezer ben Yaakov. Both agree that a non-Jew who lives in the courtyard will need to actually lease his part of the courtyard to the others in order to allow them to establish an eiruv. Rabbi Meir feels that this is necessary, even if there is only one Jew living in the courtyard; Rabbi Eliezer ben Yaakov deems this necessary only if there are two or more Jewish residents. This disagreement does not really stem from the rules of eiruv. They both agree, in principle, that the non-Jew’s presence in the courtyard does not require his participation in the eiruv. Rather, this is a Rabbinic decree whose purpose is to discourage Jews from taking up residence in a courtyard with non-Jews. Rabbi Meir believes that this decree always applies, but Rabbi Eliezer ben Yaakov points to the fact that it would be unusual for a Jew to live alone with non-Jews in their courtyard, due to his fear of the non-Jews. Therefore there was no need to establish a Rabbinic decree for such an unusual situation.
The Gemara lists several amoraim who rule like Rabbi Eliezer ben Yaakov, culminating in Abayye’s statement to Rav Yosef that the tradition is that the teachings of Rabbi Eliezer ben Yaakov are kav v’naki – short, but clear and perfect – so we follow them in every area of halakha.
The principle that the teachings of Rabbi Eliezer ben Yaakov are kav v’naki appears several times in the Gemara. There is some discussion about how broad a ruling it is. Does it apply only to his teachings that appear in the Mishna, or in baraitot, as well? Is it only true against one adversary, or even against a group? The conclusion seems to be that we will always follow the teachings of Rabbi Eliezer ben Yaakov. Tradition has it that his teachings appear 102 times in the Talmud – matching the Gematria of the word “Kav,” and that his opinion is accepted in every one of those cases.